One more BFL Asic board for fun and free design

Cheers,

I try to make my own pcb :-) Details will follow but here the first facts:

Main PCB will get µATX, ATX or E-ATX form factor
Main PSR is default ATX PSR mounted in 19" server rack which the main pcb will be mounted
BFL Chips will be solder on carrier PCB in one of actual CPU Socket form factor (e.g. LGA1155). They will get an copper heat spread on top mounted.
Every Carrier can handle one to max 7 chips (maybe 8 depends on needed adress for PSRs)
On Main PCB CPU sockets will be mounted to connect the BFL carrier and a proper CPU cooler solution
Every BFL will get there own (maybe programmable) psr (which needs one own SPI address for psr controller) with sense lines as near as possible to the chips
Option for external clock is planned (maybe need one more SPI address).
BFL Chip Controller solution is selectable: AVR or Rasberry Pi (or other)
Temperature will be measure by internal chip temp sensor
KiCad will be used for planning the layout and design.
The design files will be shared.

Ready:

Next Steps:

Open questions:

Documentation from BFL described Done signals in daisy chain mode. On SC Board instead chip done signals are directly connected to AVR. Why?
What are the possible heat spread sizes for different LGA sockets? In fact also what are the dimensions of different cpu's?
How much CPU sockets can be used on main pbc?
Maybe because of large size 2 Layer board could be used for main pcb.
Is the Rasberry Pi strong enough?
When will I get my BFL chip order in hand? In 1st week of october as promised?
How much are the costs of the more expensive parts?

My recent favorites:

8 BFL on LPGA-2011 Carrier with copper heat spread because of needed min. die size 42mm x 42 mm
8 PowerOne DP8120 POL controlled by DM7308 Power controller
Rasberry Pi as Controlller with SPI Mode for controlling BFL Chips
Fallback PSR DeltaOne D12S050201C with trim

References:

To be continued.